mckeown

Recent Results from KamLAND: 

Recent Results from KamLAND R. D. McKeown Caltech BNL – January 17, 2006

Outline: 

Outline Historical Introduction Neutrino physics Neutrino mixing and oscillations KamLAND reactor neutrino results Geoneutrinos Future prospects

Discovery of the Neutrino – 1956: 

Discovery of the Neutrino – 1956 F. Reines, Nobel Lecture, 1995

Subsequent History: 

Subsequent History 60’s and 70’s – n became the darling of accelerator-based particle physics ne ≠ nm 1968 – 1st solar n anomaly evidence 1980’s – new interest in neutrino oscillations (F. Reines, …..) 1980-present: the quest for neutrino oscillations 1998 – evidence from Super-K

Super-Kamiokande Results: 

Super-Kamiokande Results

Two Generation Model: 

Two Generation Model

Missing solar neutrinos…: 

Missing solar neutrinos…

Matter Enhanced Oscillation (MSW): 

Matter Enhanced Oscillation (MSW) Mikheyev, Smirnov, Wolfenstein

Maki – Nakagawa – Sakata Matrix: 

Maki – Nakagawa – Sakata Matrix CP violation

Pre – KamLAND summary: 

Pre – KamLAND summary Persistent observations of deficit of solar neutrinos 1998 – observation of oscillations of atmospheric neutrinos by Super-K 2002 – SNO results imply matter-dependent oscillations of solar neutrinos Time to get our feet on the ground!!

W.A. Fowler Nobel Lecture, 1983: 

W.A. Fowler Nobel Lecture, 1983

Slide15: 

Enter Long Baseline (180 km) Calibrated source(s) Large detector (1 kton) Deep underground (2700 mwe)

Neutrino Oscillation Studies with Nuclear Reactors: 

Neutrino Oscillation Studies with Nuclear Reactors ne from n-rich fission products detection via inverse beta decay (ne+pge++n) Measure flux and energy spectrum Improve detectors, reduce background Variety of distances L= 10-1000 m

Slide17: 

Detection Signal Coincidence signal: detect Prompt: e+ annihilation g En=Eprompt+En+0.8 MeV Delayed: n capture 180 ms capture time

The Reactor Neutrino Flux and Spectrum: 

The Reactor Neutrino Flux and Spectrum 235U, 239Pu, 241Pu from b measurements 238U calculated Time dependence due to fuel cycle

Precise Measurements: 

Precise Measurements Flux and Energy Spectrum g ~1-2 %

Negative Oscillation Searches: 

Negative Oscillation Searches 103 Distance (m)

The BIG picture:: 

The BIG picture: (From PDG) SK atm (nmgnt)

Slide23: 

KamLAND uses the entire Japanese nuclear power industry as a long­baseline source

Slide24: 

Many reactors contribute to the antineutrino flux at KamLAND *Eν>3.4MeV (Eprompt>2.6MeV) Detailed power and fuel Composition calculation used From electrical power Japanese average fuel used

Slide25: 

A limited range of baselines contribute to the flux of reactor antineutrinos at Kamioka Korean reactors 3.4±0.3% Rest of the world +JP research reactors 1.1±0.5% Japanese spent fuel 0.04±0.02%

Spectrum Distortion: 

Spectrum Distortion

Slide29: 

Front End Electronics Samples (~1.5ns) ADC counts (~120 mV) Blue: raw data red: pedestal green: pedestal subtracted Waveforms are recorded using Analog Transient Waveform Digitizers (ATWDs), allowing multi p.e. resolution The ATWDs are self launching with a threshold ~1/3 p.e. Each PMT is connected to 2 ATWDs, reducing deadtime Each ATWD has 3 gains (20, 4, 0.5), allowing a dynamic range of ~1mV to ~1V

Slide30: 

The KamLAND Collaboration

Slide31: 

KamLAND:timeline Summer 2000 PMT installation Jun-Sept 2001 Fill Liquid Scintillator Jan, 2002 Begin Data Taking Dec, 2002 Report 1st Physics Results Jun 2004 Report 2nd Reactor  Results Sept 2005 Report geoneutrino evidence

Slide32: 

DE/E ~ 6.2% /√E , Light Yield ~ 300p.e./MeV DEsyst = 2.0% at 2.6 MeV

Slide33: 

Tagged cosmogenics can be used for calibration 12B 12N Fit to data shows that 12B:12N ~ 100:1 τ=29.1ms Q=13.4MeV τ=15.9ms Q=17.3MeV μ

Slide34: 

Energy calibration uses discrete γ and 12B/12N 68Ge 65Zn 60Co n-p Carefully include Birks law, Cherenkov and light absorption/optics to obtain constants for γ and e–type depositions n-12C σ/E ~ 6.2% at 1MeV

Slide35: 

z Vertexing is performed using timing from the 17” PMTs -65 (1.1MeV) -68 (1.0MeV) -60 (2.6MeV) Am/Be(~8MeV)

Slide36: 

neutrons Fraction of volume inside the fiducial radius verified using μ-produced 12B/12N and n (assumed uniform) 12B/12N

Slide37: 

Estimate of total volume and fiducial fraction

Singles Background: 

Singles Background 14C:? 210Pb: 102Hz:-- 85Kr: 606 Hz:-- 40K:1.9Hz:2.1Hz 208Tl: 3.2Hz:1.4Hz 232Th, cosmogenic: 0.19Hz High Energy (e.g. μ): 0.33Hz:0.33Hz Source:Measured:Predicted

Slide40: 

- Rprompt, delayed < 5.5 m - ΔRe-n < 2 m - 0.5 μs < ΔTe-n < 1 ms 1.8 MeV < Edelayed < 2.6 MeV 2.6 MeV < Eprompt < 8.5 MeV Tagging efficiency 89.8% …In addition: 2s veto for showering/bad μ 2s veto in a R = 3m tube along track Dead-time 9.7% Selecting antineutrinos, Eprompt>2.6MeV (543.7 ton) 5.5 m fiducial cut Balloon edge

Slide45: 

Observed Event Rates 2002-4 dataset 766.3 ton•yr, Eprompt > 2.6 MeV Observed: 258 events No-oscillation: 365.2 ± 23.7 events Background 17.6 ± 7.2 events accidental 2.69 ± 0.02 9Li/8He (b, n) 4.8 ± 0.9 fast neutron < 0.89 13C(a,n) 10.0 ± 7.1

Slide46: 

99.998 % C.L. Evidence for Reactor ne Disappearance!!

Slide48: 

Ratio of Measured and Expected ne Flux from Reactor Neutrino Experiments

Oscillation Effect: 

Oscillation Effect

Correlation with reactor power variation: 

Correlation with reactor power variation

Slide52: 

KamLAND best fit : Dm2 = 7.9 x 10-5 eV2 tan2q = 0.45

Slide53: 

+

Combined fit with solar neutrino data: 

Combined fit with solar neutrino data Dm2=7.9+0.6-0.5x10-5 eV2 tan2q=0.40+0.10-0.07

Solar Neutrino Results: 

Open circles: combined best fit Closed circles: experimental data Solar Neutrino Results

Geoneutrinos – the early history: 

Geoneutrinos – the early history

More recent references: 

More recent references

Geoneutrinos: 

Geoneutrinos U/Th/K in crust/mantle - amount of activity - distribution Energy budget – heat generation - plate tectonics - magnetic field Structure of earth’s core - constrain models - georeactor?

Inside the Earth: 

Inside the Earth

U/Th Distribution: 

U/Th Distribution

Geoneutrino spectrum: 

Geoneutrino spectrum

The predicted sources of geoneutrinos: 

The predicted sources of geoneutrinos

KamLAND Data: 

KamLAND Data U Th Reactor n 13C(a,n) Randoms

Confidence Intervals: 

Confidence Intervals

The press was interesting…: 

The press was interesting… Hindustan Times, August 8, 2005

Slide69: 

And finally:

KamLAND Future: 

KamLAND Future Precision Reactor Neutrino Measurements - 4p calibration system - refine analysis methods - more statistics Supernova detection Precision Solar Neutrino Measurements - radiopurity - low energy threshold More precise geoneutrino measurement

Neutrino-proton elastic scattering: 

Neutrino-proton elastic scattering e e ,  ,, 